Protect the Control Service › Switch the Roles of the Active and Standby Control Services › The Switchover and Backward Scenario Processes

The Switchover and Backward Scenario Processes

Understanding the switchover and backward scenario process

1. Since the original active Control Service is down, the Overview Page and Manager are no longer connected to it. Therefore, they no longer receive and display updated information, and the changes that occur following the switchover initiation are not shown in them, as they are shown in a regular switchover.
2. When the Overview Page loses its connection to the original active Control Service, the following message opens.

   This message indicates that the original active Control Service is down, and therefore it is no longer connected to the Overview Page.

3. Click OK to close the message. This message may appear several times until the original standby Control Service becomes active, and a connection to it is established.
4. When the original standby Control Service is up and functioning as the new active Control Service, the Overview Page is automatically reconnected to it, and the Login dialog appears, prompting you to login to the new active Control Service.
5. Enter your User Name, Password and Domain and click the Log In button.

   The Overview page re-appears, and it is now connected to the new active Control Service.

6. On the Manager, the User Credentials dialog may open.

   The User credentials dialog prompts you to login to the new active Control Service. If this dialog appears, enter the necessary details and click OK.

   Note: The appearance of the User credentials dialog is related to internal caching settings, and it is not necessarily an indication to the progress of the switchover process. The switchover may take place even if the User credentials dialog does not appear.

7. The two Control Services have switched roles. Now, the Manager is no longer connected to the original active Control Service but to the standby Control Service, which became active following the switchover. The switchover related-events are displayed in the Event pane.

   Note: The "Split Brain" problem and solution:

   After a connection loss and a switchover, the original standby Control Service is functioning as the active Control Service. However, the original active Control Service may still be up. Upon reconnection, both Control Services may try to act as the active Control Service. In order to solve this potential problem, CA ARCserve RHA keeps built-in numerical parameter in each Control Service, and the switchover process increases the number of the newly active Control Service. All connection requests are sent with this parameter, and when a Control Service receives a connection request, it checks whether it contains a lower or higher number than the one it carries. The Control Service that carries the lower number, shuts itself down, and becomes the standby Control Service.

8. After the switchover, a backward scenario is automatically initiated by the system.
9. The backward scenario starts running once the original active Control Service is up. It replicates data from the new active Control Service to the new standby Control Service, while overwriting the data on the current standby Control Service.
10. Now, you can switch back the roles of the active and standby Control Service, and make the original Master the active server again and the Replica the standby server.